The present invention generally relates to an ultrasonic probe which projects an ultrasonic wave onto. a living human body and receives a beam reflected from inside the body, so that information related to the body can be obtained from the reflected beam. More particularly, the present invention is concerned with an ultrasonic probe having a rotary refracting member.
Conventionally, a diagnostic method using an ultrasonic probe is used to obtain information inside of the living human body. An ultrasonic probe is inserted into a part of a living human body, for example, a blood vessel, and the inside thereof is scanned by an ultrasonic beam emitted from the ultrasonic probe.
FIG. 1A illustrates a first conventional ultrasonic probe, which has a plurality of piezoelectric elements 11 supported in a rotary disk. When the piezoelectric elements 11 are rotating, each of them emits an ultrasonic beam within a sectorial area A.
FIG. 1B illustrates a second conventional ultrasonic probe. A plurality of piezoelectric elements 12 are aligned and supplied with pulse signals 13 having mutually different element driving times, so that an ultrasonic beam is deflected in the sectorial area A.
FIG. 1C illustrates a third conventional ultrasonic probe. A plurality of piezoelectric elements 14 are arranged on a curved surface portion and are successively driven by the driving pulses, so that an ultrasonic wave, deflected in the sectorial area A, can be obtained.
FIG. 1D illustrates a fourth conventional ultrasonic probe. A piezoelectric element 15 emits an ultrasonic beam while it is being rotated, so that the ultrasonic beam is radially deflected.
FIG. 1E illustrates a fifth conventional ultrasonic probe. A piezoelectric element 16 emits a ultrasonic beam, which is reflected by a rotary reflector 17, so that the ultrasonic beam is radially deflected.
However, the above-mentioned first through fifth conventional ultrasonic probes have the following disadvantages. Since the piezoelectric elements are rotated, it is necessary to provide a magnetic coupling device which magnetically couples the piezoelectric elements with an external device. Thus, it is very difficult to produce a compact ultrasonic probe which is small enough to be inserted into a blood vessel having a diameter between approximately 3-10 mm.
It is also very difficult to produce a compact ultrasonic probe having the structure shown in FIG. 1B or FIG. 1C, because it is necessary to produce an array of small piezoelectric elements. In addition, it is very difficult to connect lead lines to the small piezoelectric elements.
It is possible to produce a compact ultrasonic probe having the structure shown in FIG. 1D or FIG. 1E. However, each of the ultrasonic probes shown in FIGS. 1D and 1E can only scan a plane substantially perpendicular to the rotating axis. Thus, it is impossible to obtain information related to an object located in front of the ultrasonic probe.
As shown in FIG. 2, a ultrasonic probe 22 used in the medical field is inserted into, for example, a blood vessel 21. In this state, it is required that an ultrasonic beam be forwardly emitted from the ultrasonic probe 22 in a sectorial area 23, so that two-dimensional or three-dimensional sectional images can be obtained.
On the other hand, as shown in FIG. 3, there is a need for an ultrasonic probe capable of focusing the ultrasonic beam at any point in a focus range 32 between focus points 33 and 34. Each of the structures shown in FIGS. 1B and IC will meet such a need. However, as has been pointed out previously, it is very difficult to provide a compact ultrasonic probe.